[Bug c/25509] can't voidify __attribute__((warn_unused_result))

[rguenth at gcc dot gnu dot org]

------- Comment #10 from rguenth at gcc dot gnu dot org  2005-12-21 10:16 
-------
This "fixes" it:

*** gimplify.c  (revision 108853)
--- gimplify.c  (working copy)
*************** gimplify_expr (tree *expr_p, tree *pre_p
*** 4203,4210 ****
              break;
            }

!         if (VOID_TYPE_P (TREE_TYPE (*expr_p))
!             || fallback == fb_none)
            {
              /* Just strip a conversion to void (or in void context) and
                 try again.  */
--- 4203,4211 ----
              break;
            }

!         if ((VOID_TYPE_P (TREE_TYPE (*expr_p))
!              || fallback == fb_none)
!             && ! TREE_CODE (TREE_OPERAND (*expr_p, 0)) == CALL_EXPR)
            {
              /* Just strip a conversion to void (or in void context) and
                 try again.  */

it makes the gimplifier output

main ()
{
  int D.1519;
  int D.1520;

  D.1519 = foo ();
  D.1520 = 0;
  return D.1520;
}

instead of (with the (void) cast removed):

main ()
{
  int D.1519;

  foo ();
  D.1519 = 0;
  return D.1519;
}

The question whether this is an appropriate fix or just my astonishing ability 
to find ugly workarounds remains to be answered ;)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25509